GHR106 monoclonal antibody was generated in mice immunized against synthetic peptides corresponding to the extracellular domains of human GnRH receptor and was found to behave as a GnRH agonist, but with a much longer half-life than agonists known in the art. GnRH agonists have been used to treat a variety of problems such as ovulation disorders, endometriosis, uterine fibroids, precocious puberty, and some types of cancers.
The murine mAb, GHR106, including the amino acid sequence of its variable regions, is described in PCT publication WO2011/026242, the disclosure of which is incorporated herein by reference, in particular as to uses of antibodies with specificity similar to that of GHR106.
Biochemical and immunological experiments demonstrate that GHR106 has high specificity and affinity to GnRH receptor. In vitro apoptotic and anti-proliferative assays were performed to document that GHR106 reacts with the surface of almost all cancer cells or cancerous tissues in humans. Complement-dependent cytotoxicity can be induced in cancer cells in the presence of GHR106 at concentrations in the range of μg/ml. In vivo growth inhibition by GHR106 of tumor cells implanted in model systems was also demonstrated in nude mouse experiments.
For use of GHR106-based anti-cancer drugs or fertility regulation drugs in humans, it is essential to modify the original murine GHR106 monoclonal antibody into humanized forms.
Disclosure of the Invention
The humanized versions of GHR106 of the invention were shown to have affinities and specificities to GnRH receptor which are comparable or equivalent to those of original murine GHR106.
Thus, in one aspect, the invention is directed to humanized antibodies or fragments that bind the epitope present in residues 1-29 in the extracellular domain of the human GnRH receptor, with specificities and affinities substantially equivalent to that of GHR106. In particular, the antibodies or fragments with variable regions shown in FIG. 6 are part of the invention.
For complete antibodies of the invention, it is preferred that the constant region of the heavy chain be IgG and the constant region of the light chain be kappa. However, other Ig forms, including IgM, IgA and IgE for example, are included as well as those embodiments that have lambda constant regions in their light chains.
In still other aspects, the invention is directed to methods to use the antibodies of the invention in the treatment of cancer and controlling reproduction in human subjects.